I have found a not explicable (to me) content of /etc/default/dropbear, that in my findings repleaces any variable/content of the startup script of dropbear /etc/init.d/dropbear. That makes the daemon not customizable as I did previously / on other images.

The content that makes the problem is:
that goes to repleace the startup script's:
and to me creates the problem.
Infact, I wanted to run dropbear customizing the startup script, specifically using:
and this is impossible because the startup script doesn't start any dropbear but tries to run that /bin/true with the various args. Don't know what /bin/true represents honestly.
I tried troubleshooting the problem and came to a solution here , in short I emptied the /etc/default/dropbear file, but I'm still unsure if it's a bug or not. In fact dropbear -i runs itself also, together with my one /usr/sbin/dropbear -d .. -r .. -p 45 -s, and this seems to suggest another dropbear script runs somewhere otherwise this wouldn't be possible.

I await your illumination

forgot to mention I'm speaking about DE 4.0 001-r02 2-9-2012 on a dm8000.